The present invention relates to an improvement in a spark plug for internal combustion engines.
In the conventional spark plug, a generally L-shaped ground electrode is welded at one end to the lower skirt margin of the threaded shell of the plug, so that the free end of the ground electrode ties just below the exposed end of another electrode which is supported concentrically in the shell within a cylindrical block of insulating material. The ground electrode usually consists of a solid flat bar of metal so that when the gaseous fuel is ignited by a spark across the gap between the two electrodes, a portion of the expanding gas is blocked in its passage towards the piston by having to pass around and over the sides of the ground electrode. This delayed passage results in imperfect combustion of the gases and contributes appreciably to pollution when one considers the frequency of the explosions taking place in each cylinder of a modern engine.